Step 1: Pay attention to babblingPay attention to when your baby begins to babble. They should start at around five months old.

Step 2: Monitor eye contactBegin monitoring eye contact at around six to nine months, when infants generally start smiling in response to their parents' grins. Babies with autism tend to avoid looking at their parents.

Step 3: Try some gamesIf your baby makes a sound, make one back and see if they reciprocate. Babies with autism usually do not take part in this verbal turn taking, nor do they participate in peek-a-boo.

Step 4: Try to get their attentionNote whether your baby responds to their name: They should begin to do so starting around 10 months.

Step 5: Check for 12-month milestonesBy this point, most babies are pointing, waving, grasping objects, and attempting to speak.

Step 6: Gauge their sensitivityGauge your baby's sensitivity to sound and touch. Many children with autism are unusually sensitive to loud noises & hate being cuddled or touched—yet they sometimes under-react to pain.

Step 7: Study their focusDo they tend to fixate on a favorite object, or part of an object, to the exclusion of other people, including other toddlers?

Step 8: Notice repetitionSuch as rocking back and forth, hand flapping, and twirling.

Step 9: Notice rigidityChildren with autism often exhibit strong resistance to changes in their routine.

Step 10: Count their wordsKeep track of vocabulary. At 18 months, most babies can say about a dozen words, and by the 2-year mark, they are usually initiating 2-word phrases.